The present invention relates to walk-behind self-propelled mowers and more particularly relates to drive wheel mountings for such mowers.
Generally, self-propelled mowers are provided with an engine having a vertical output shaft on which the mower blade is fixed and on which a gear or pulley forming part of a propel drive for the mower is fixed. These propel drives normally include a cross-shaft coupled to be selectively driven from the gear or pulley.
In some propel drives, such as that illustrated in U.S. Pat. No. 2,688,224 issued to Hainke on Sept. 7, 1954, the drive wheels are fixed directly on the ends of the cross-shaft and the cross-shaft is carried by vertically adjustable brackets which effect changes in the cutting height of the mower. Drives of this type have the disadvantage that the drive components coupling the engine output shaft with the cross-shaft must be designed to allow the cross-shaft to be adjusted vertically.
In other propel drives, such as those illustrated in U.S. Pat. No. 2,941,610 issued to Clemson on June 21, 1960 and U.S. Pat. No. 2,996,134 issued to Muerle et al on Aug. 15, 1961, the cross-shaft is rotatably mounted in the main frame of the mower and has gears fixed on its opposite ends and meshed with gears fixed integrally to the drive wheels. The drive wheels are rotatably mounted on stub shafts fixed to brackets mounted for vertical pivoted adjustment about the axis of the cross-shaft. These drives sometimes suffer the disadvantages that the wheels wobble on the stub shafts thus resulting in increased wear between the gears carried by the wheels and the gears fixed to the cross-shaft.
Another disadvantage of both of the aforementioned types of prior art designs is that the wheels must be individually adjusted to alter the cutting height of the mower.